New Players Become Available Done 

During the season, many new players get added to the fantasy player pool. Mostly, these are minor leaguers who appear after they are officially placed on a Major League roster. Occasionally, Yahoo adds minor leaguers to the game before they are officially called up because their Major League debut is widely reported to be imminent. If you prefer all new players to be added to the game the same way, choose "Wait until called up to Majors." If you prefer players to be added to the game immediately, choose "As soon as Yahoo adds them."